Negative Split Calculator
Plan a negative split by choosing how much faster to run the second half of your race.
How to use the negative split calculator
- Enter the race distance and your goal finish time.
- Choose how much faster (%) you want the second half to be.
- Click Calculate to get first- and second-half times and paces.
Why negative splits work
Starting slightly controlled preserves glycogen and limits early lactate accumulation, leaving more in the tank to accelerate when others are fading.
Frequently asked questions
What is a negative split?
A negative split means running the second half of a race faster than the first. It is a hallmark of well-paced distance running and most world records.
How much faster should the second half be?
A modest 1–3% is realistic for most runners. Larger negative splits usually mean the first half was run too conservatively.
Related tools
Marathon Pace Calculator
Enter a goal marathon finish time to get the pace you need to hold, your halfway target, and cumulative splits.
Half Marathon Pace Calculator
Enter a goal half marathon finish time to get your required pace, halfway split, and cumulative split targets.
Pace Calculator
Enter any two of distance, time, and pace — get the third instantly, plus per-km and per-mile splits.